So we have a diamond that kills you. Right now there's no origin, backstory or other hook to keep the reader interested. Make sure that your SCP is more than a magical/deadly item. Where was this found? Is it intentionally created? Do we know who's behind it? Things like that. Keep in mind that you don't actually have to blatantly answer these questions. Instead, give us enough information to keep the reader interested, but not enough to 'spoil' it.

Thank you for your feedback, I am currently working to fix things that were pointed out, and trying to think of a backstory. It really helps to have good feedback so that I can work hard to make it better!